02074nas a2200289   4500000000100000008004100001260001500042653001800057653002300075653001700098653001700115653002500132653001500157653002800172653002000200653001100220653002700231100001500258700001600273700001800289245012700307856007200434300001100506490000800517520124500525022001401770       2022                            d  c2022-09-0110aBreast cancer10aCell heterogeneity10acytotoxicity10adrug testing10aextracellular matrix10ametastasis10aMicrofluidic technology10aorgan-on-a-chip10aStroma10aTumor Microenvironment1 aRita Kalot1 aRami Mhanna1 aRabih Talhouk00aOrgan-on-a-chip platforms as novel advancements for studying heterogeneity, metastasis, and drug efficacy in breast cancer  uhttps://www.sciencedirect.com/science/article/pii/S016372582200050X  a1081560 v2373 aBreast cancer has the highest cancer incidence rate in women worldwide. Therapies for breast cancer have shown high success rates, yet many cases of recurrence and drug resistance are still reported. Developing innovative strategies for studying breast cancer may improve therapeutic outcomes of the disease by providing better insight into the associated molecular mechanisms. A novel advancement in breast cancer research is the utilization of organ-on-a-chip (OOAC) technology to establish in vitro physiologically relevant breast cancer biomimetic models. This emerging technology combines microfluidics and tissue culturing methods to establish organ-specific micro fabricated culture models. Here, we shed light on the advantages of OOAC platforms over conventional in vivo and in vitro models in terms of mimicking tissue heterogeneity, disease progression, and facilitating pharmacological drug testing with a focus on models of the mammary gland in both normal and breast cancer states. By highlighting the various designs and applications of the breast-on-a-chip platforms, we show that the latter propose means to facilitate breast cancer-related studies and provide an efficient approach for therapeutic drug screening in vitro.  a0163-7258